Soil correctives



eased Dec. 4. 1945 'son. coaanc'rrvas Albert C. Mohr, Arcadia, Calm, assignor to Stanfiel- Chemical Company, a corporation of California Serial No. 478,131

No Drawing. Application Mmh'5, 1943,

6 Claims.

This invention relates to soil additive materials designed to correct and improve the acidity of soil.

It has been recognized in recent years that the I acidity or alkalinity of a soil should be altered to improve the workability of the soil, as well as its productivity. To this end, various materials are frequently added to soils. However, these materials are comparatively slow, depending upon action in the soil for liberation of acidifying constituents. This is particularly true in the case of the addition of sulphur or gypsum to' the soil.

Direct acidification with the sulphuric acid of commerce, while highly desirable, is generally im-' practical because. of corrosion on equipment, and because this material cannot be handled by farm labor cheaply, economically and with any degree of safety. Further, the use of sulphuric acid in a dilute condition involves use of special equipment and, unless handled correctly, may be hazardous to the unskilled. Finally, direct acidification must be done very exactly or serious overdosing may occur.

There are available various industrially exhausted sulphuric acids which are commonly treated to recover the sulphur. values therein. I

formed. The operation is so conducted that the coke removed irom the furnace is dry and tree fiowing. It can contain between about 10% and about 50% water soluble sulphuric acid.

have discovered that a suitably treated acid can serve as a source of sulphur dioxide for subsequent industrial recovery and, at the same time, a coke residuecan be formed which can be handled as a solid and which is acceptable as a soil additive. The coke is dry, granular and freeflowing, and can be conveniently handled in ordinary equipment. The coke has such high absorptive properties that it will hold up to half its weight of sulphuric acid and-still remain dry. The coke can be produced with the acid present or the acid can be added separately.

To form the soil additive oi-the present invention, I take a suitable sulphuric acid, one containing sufilcient carbon and hydrogen, usually as hydrocarbonaceous material, to form a coke residue on partial desulphurization. This is subject to a thermal de-sulphurization treatment under conditions such that a coke residue containing water soluble sulphuric acid is present in the coke. Such a process is disclosed in my copending application Serial No. 474,345 filed February 1, 1943, and in the application of Ross and Wilde Serial No. 453,242 filed August 1, 1942. As is there disclosed, sulphuric acid industrially exhausted in an alkylation process is treated in a suitable furnace under conditions such that the coke is heatedto a moderately high temperature, between 500 and'600 F., and a coke residue is In place of using the process disclosed in the aforesaid applications, one can use any other process wherein a, coke residue is formed, care being taken to permit or to ensure thepresence in the coke residue of the desired quantity of water soluble sulphuric acid. The use oi the process of the applications is, however, particularly desirable because the acid is heated in an atmosphere which does not contain air. This ensures that hydrocarbons present are driven or! from the coke and the coke is then nothing but an inert carbon mass which can be added to the soil without harm. Any suitable exhausted acid can be employed, such as a pressure distillate sludge or other acid sludge, so long as the acid content is high enough to permit a dry granular coke to be formed that contains the desired percentage of H2804.

After the coke has been produced it is 01 course removed from the furnace and permitted to cool; if allowed to stand the sulphuric acidwill take up water. I have found that by mixing into the coke suillcient of an inert coating material, such as diatomaceous earth fines, clay, talc or the like, to coat the coke particles, the coke mass is cooled sufiiciently to permit it to be packaged immediately in airtight containers. It can then be readily handled and shipped. This makes possible the use of ordinary multiple paper bag structures of commerce. With diatomaceous earth fines, about 10% by weight usually sufiices.

The present material is quite unique in that if .it is attempted to add sulphuric acid to ordinary The material of this invention is readily applied wherever desired to correct the pH of the soil, the material being scattered and spread and then worked into the soil. The sulphuric acid dissolves out of the coke, while the coke disin'tegrates in the soil to provide a light, inert diluent imthat greater aeration oi. the soil can be achieved. Because the coke is spread by machine or by hand quite easily and with considerable accuracy, the correct dosage in any selected area can be secured quite readily.

The dosage of the additive will depend on the degree of correction or acidification required. Because of the small, uniform size of the granules (usually all the granules will pass an 8 mesh screen while nearly all will be retained in a 100 mesh screen) the additive is readily spread by hand or by mechanical means. In addition, the small sizeenables read control or the dosage. Further, it can be applied close to the base of plants and trunks of trees without injury to these.

I claim:

'1. A process for treating soil comprising disv tributing on the soil and working therein a dry granular coke produced by the partial desulphurization of sulphuric acid sludges derived from petroleum treatment, said coke being substantially .iree of oil hydrocarbons and containing between about and 50% by weight of water soluble sulphuric acid.

2. Ai process for treating soil comprising distributing on the soil and working therein a dry granular coke produced by partially thermally desulphurizing a, sulphuric acid sludge by heating said sludge derived from petroleum treatment in the substantial absence of air to form a dry granular coke substantially free of oily hydrocarbons and containing water soluble sulphuric acid and removing the coke formed by said thermal desulphurization while it contains a substantial quantity of water soluble sulphuric acid.

3. A process for treating soil comprising dis tributing on the soil and working therein 'a dry 2,890,204 proving and lightening the densityof the soil so" granular coke produced by thermally desulphurizing a sulphuric acid sludge derived from pe-- I troleum treatment by heating said sludge in the substantial absence 0! air to form a dry granular coke substantially free of oil hydrocarbons, removing the coke termed by said thermal desulphurization and adding sulphuric acid to the coke in an amount up to about 50% oi the weight of the coke.

4. A process for. treating soil comprisingdistributing on the soil and working therein a dry granular coke produced by the partial desulphurization o alkylation acid sludge. said coke being substantially tree of oilhydmcarbons and containing between about 5% and 50% by weight of water soluble sulphiu'ic acid.

5. A process for treating soil comprising distributing on the soil and. working therein a dry granular coke produced by partially thermally desulphurizing an alkylation sulphuric acid sludge by heating said sludge in the substantial absence of air to form a dry granular coke substantially free of oily lwdrocarbons and containing water soluble sulphuric acid and removing the coke formed by said thermal desulphurization while it contains a substantial soluble sulphuric acid.

6. A process for treating soil comprising distributing on the soil and working therein a dry granularcoke produced by thermally desulphurizing an alkylatlon sulphuric acid sludge by heating said sludge in the substantial absence 01' air a to form a dry granular coke substantially free of oil hydrocarbons, removing the'coke formed by said thermal desulphurization and adding sulphuric acid to the coke in an amount up to about coke.

quantity of water 

